How to design and implement a blocking queue?

Question:

Blocking queue related question often gets asked from Google, LinkedIn. For example, iImplement a fixed size blocking queue with the following defined functions. By blocking queue it Blocking queue related question often gets asked from Google, LinkedIn. means if the queue is empty, the dequeue thread should be blocked until some other thread enqueue anything. If the queue is full then the enqueue thread gets blocked until the dequeue thread dequeue anything from the queue.

Here is the API defined.

public interface FixedSizeBlockingQueue<E> {

// only initialize this queue once and throws Exception if the user is trying to initialize it multiple t times.

public void init(int capacity) throws Exception;

// throws Exception if the queue is not initialized

public void push(E obj) throws Exception;

// throws Exception if the queue is not initialized

public E pop() throws Exception;

// implement an atomic putList function which can put a list of object atomically. By atomically it mean the objs in the list should be next to each other in the queue. The size of the list could be larger than the queue capacity.

// throws Exception if the queue is not initialized

public void pushList(List<E> objs) throws Exception;

}

Analysis:

Here we are using some basic OS and JVM primitives to implement a blocking queue. Basically it is using monitor and lock. Java exposes those two OS primitives to programmers as Condition and ReentrantLock. Here is the explanation from Java Doc